1. Technical Field
This application relates generally to a power converter whose casing is made of an assembly of a first case and a second case and which has a capacitor mounted in a storage chamber defined inside the casing.
2. Background Art
Japanese Patent First Publication No. 2009-201257 discloses a power converter, such as an inverter mounted in electric vehicles or hybrid vehicles, which has a capacitor mounted within a converter casing. The capacitor is made of a capacitor casing and a capacitor device disposed in the capacitor casing and sealed with potting resin. The potting resin is partially exposed outside the capacitor casing to have a potting surface. The capacitor is mounted on a base with the potting surface facing the surface of the base.
Usually, the potting surface defines a major surface which is the greatest in area of the capacitor. Thus, the arrangement of the capacitor with the potting surface directly placed on the base will cause the capacitor to occupy a great area of a parts-mounting surface of the base, which requires a need for widening the parts-mounting surface of the base in order to secure an area for other parts. This leads to a difficulty in decreasing the size of the power converter in a planar direction of the capacitor.
In view of the above problem, it may be proposed to arrange the capacitor on the base with the potting surface oriented perpendicular to a normal direction of the base (i.e., a bottom of the converter casing) in order to make efficient use of a storage space in the casing and facilitate a decrease in size of the power converter. Such an orientation of the potting surface is also desirable in terms of simplicity of layout of terminals of the capacitor in the case where the terminals of the capacitor protrude from the potting surface and are joined to a switching circuit or a reactor arranged away from each other in the planar direction of the bottom of the casing.
The arrangement of the capacitor with the potting surface oriented perpendicular to the planar direction of the bottom of the converter casing, however, may result in a problem that facilitates the physical vibration of the capacitor. Specifically, the mounting of the capacitor on the converter casing is achieved by securing the capacitor casing to the bottom of the converter casing. It is usually impossible to secure an area for the securement of the capacitor casing on the potting surface. The capacitor casing is, therefore, fixed on an area of the bottom of the capacitor casing other than the potting surface. It is difficult for such an arrangement of the capacitor casing to avoid the physical vibrations of the capacitor in a direction in which the capacitor leans toward the potting surface when the power converter is subjected to mechanical vibrations. For instance, when the vehicle vibrates, it may increase the vibrations of the capacitor toward the potting surface, which results in an increase in physical load on terminals of the capacitor which connect with other parts.